RICHMOND, Va. (AP) - Legislation that prohibits health insurers from holding proton radiation cancer therapy to a higher standard of clinical effectiveness than other radiation treatments is advancing in the General Assembly.

A Senate committee approved the measure Monday. It has already passed the House of Delegates by a wide margin.

Proton therapy is a highly targeted, FDA-approved form of radiation that's used to treat a variety of cancers while sparing surrounding healthy tissue, resulting in fewer side effects.

The bill's sponsor, Del. David Yancey, says lawmakers in Oklahoma approved a similar bill in 2015.

Supporters included cancer patients and people whose relatives died of cancer.

A representative of the Virginia Association of Health Plans says proton therapy isn't evaluated differently but studies have shown it's not as effective for certain types of cancers.